The answer to that question is obviously no BUT............. There are a ton of RTC's kept for life in much smaller tanks. I have a theory on keeping these big fish, so here goes........
Every week I see a new baby RTC get sold at my LFS and although I'm not sure where they all go, I am sure they are not all going to a 3000 gallon indoor pond in the Governors mansion. I also very rarely see them returned to the LFS as the unwanted 4' monsters I keep hearing about on this sight "actually never". So that leaves me to think.....
A.... Most of these fish die before they get big.
B.... A lot more people have huge tanks than I thought.
C.... These fish dont get as big as most people think.
D.... They must taste pretty good with french fries.
I currently own a couple RTC's and I'm sure the housing I provide for them whether it be my 265 gallon tank or my 180,150 wide,125 ect....... is better than they would recieve 95% of the time from someone else. My water quality is as good as it gets, they are fed well, and have always had plenty of room to move around. My 30+" RTC lived in a 180 for 8 years and was healthy and seemed to be very happy. Sure a 10,000 tank would have been better but I did the best I could and for 8 years, provided him a dam good life. At the time I also had a 2500 gallon indoor pond, and the RTC I kept in that just stayed in the corner and only swam around when he was hungry

.
I think more emphasis should be paid to quality of care not just tank size. Regardless of what goes on RTC's are gonna be sold. If you do not buy that cute little 2" guy for $20 because your 180 gallon tank "is too small" some little kid WILL buy him for his 20 gallon community tank with battery acid for water. Either way that fish is getting sold. I consider an EDUCATED fishkeeper regardless of his tank size a blessing to these little RTC's and the hobby. BUT.........You come on here and mention keeping one and you get blasted
Bottom line ....... The bigger the better, but more importantly keep them healthy and provide the best water quality and conditions possible.
JMO of course.......
FIRE AWAY
bob